(a) Field of the Invention
The present invention relates to an optical-axis adjusting apparatus for use with automotive lights such as headlight, fog light, etc., and more particularly to an optical-axis adjusting apparatus easily assemblable to and securely retainable by such lamp unit.
(b) Prior Art Statement
The optical-axis adjusting apparatus for use with automotive lights generally include two types: In one of these types, the entire lamp unit including the reflector is rotatable about the horizontal and vertical axes to adjust the optical axis, namely, to orientate the light beam from the lamp unit, and in the other type, the reflector inside the lamp unit is freely rotatable about the horizontal and vertical axes for the same purpose. Particularly, in the optical-axis adjusting apparatus of the former type, the lamp unit as a whole is pivotably supported by means of a pivot assembly to a support member for attachment to a motor vehicle and threaded shanks in a pair each having one end thereof pivotably fitted in the back of the lamp unit and screwed in an internally threaded member fixed to the support member are provided to tilt the lamp unit about the horizontal and vertical axes, respectively, thereof, thereby adjusting the position of the lamp unit. For example, as disclosed in the U.S. Pat. No. 3,823,314 for a lamp assembly, each of the threaded shanks has formed at the end thereof a ball which is received in a part-spherical recess formed in a part of a coupling piece engaged in a flange fixed to the support member, and each of the threaded shanks is screw-threaded in a nut member secured to the support member. Thus, as any one of the threaded shanks is moved forwardly or reversely, the lamp unit is tilted about the horizontal or vertical axis. These coupling pieces are made of a synthetic resin, and each consists of a hollow body portion and a rectangular head portion interconnected by means of a cylindrical neck portion. The neck portion of the coupling is inserted in a slot formed in a part of the flange, and the hollow body and rectangular head engage with the respective surfaces of the flange with the slotted portion of the flange being between the hollow head portion and rectangular head portion which oppose each other, so that the coupling piece is prevented from moving in relation to the flange in a direction perpendicular to the flange. Also, a pair of opposite edges of the head portion of the coupling piece engage with the opposing side walls, namely, upstanding walls, of the flange so that the coupling piece is prevented from rotating in relation to the flange.
In such conventional lamp assembly, since the neck portion of the coupling piece has a diameter larger than the wide of the narrowed region of the slot and the coupling piece and flange are elastic, the neck portion is to be forcibly pressed beyond the narrowed region of the slot for movement to the final position.
With such a construction of the conventional lamp assembly, the diameter of the neck portion of the coupling piece must be larger than the width of the narrowed region of the slot within a certain range and it is difficult to implement such a geometry maintaining the certain range in consideration. If the dimensional relation between the diameter of the neck portion and the width of the narrowed region of the slot is not proper, a large load will apply to the projections of the flange which are in contact with the neck portion of the coupling piece, resulting in a deformation of the projection, or on the contrary, in a weakened coupling of the coupling piece with the flange. So, the threaded shanks can not withstand the repeated forward and reverse movement.